1. Field
Example embodiments relate to semiconductor memories and, more particularly, to nonvolatile memory devices and erasing methods thereof.
2. Description of the Related Art
A semiconductor memory device is a memory device that is implemented with semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and indium phosphide (InP). Semiconductor memory devices may be largely divided into a volatile memory device and a nonvolatile memory device.
The volatile memory device is a memory device in which stored data is erased when a power source is shut off. Examples of volatile memory devices include Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM) and Synchronous Dynamic Random Access Memory (SDRAM). A nonvolatile memory device is a memory device that retains stored data even when a power source is shut off. Examples of nonvolatile memory devices include Read-Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), Electrical Erasable Programmable Read Only Memory (EEPROM), flash memory devices, Phase-change Random Access Memory (PRAM), Magnetoresistive Random Access Memory (MRAM), Resistive Random Access Memory (RRAM) and Ferroelectric Random Access Memory (FRAM). Flash memory devices may be largely categorized into a NOR type and a NAND type.